Interface dipole metal-molecule

[jalmeida]

Dear 

Please, How should I calculate the interface dipole? My system is a gold 111 surface + molecule.

I saw some tutorials which talk about interface dipole calculation from ElectronDifferenceDensity but without too much discussion (e.g. https://docs.quantumatk.com/tutorials/nisi2-si/nisi2-si.html).

Is this the best way to calculate it? Is there another way? How can I get the interface dipole value?

Best
Joseane

[Anders Blom]

I don't think there is a unique definition of this, but a common way to consider it would be to look at the electron density in the direction perpendicular to the interface. If there is a clear separation of charge, such as positive on the left and negative on the right, you could pick some distance from the interface and integrate all net charge on each respective side. Again, as with many such quantities, just computing it for a single system has limited value, but comparing the results for different cases (added dopants, applied bias, temperature) can yield useful insights.

[jalmeida]

All right, Thank you. Until now I am calculating the electronic density difference (fulll system density - gold density - molecule density) so I can know the reorganization of density around the surface. Then, I expand the density in multipoles and I take the dipole contribution using the script already provided in the documentation: (https://docs.quantumatk.com/manual/Types/ElectronDensity/ElectronDensity.html#electrondensity)

Is that a good way?

[Anders Blom]

If those results allow you to draw conclusions, then yes